I have designed a fairly simple EMG circuit and it works fine when I give a sine input from signal generator, i.e, I can see a clear and steady sine wave at the output of AD8221 amp. When I connect the inputs to my muscle on my forearms, the signal is clearly visible before and then diminishes to zero over 3 to 4seconds. I am pretty sure that my muscles are not facing fatigue. May I know if there is anything that I missed?
bandwidth of the signal - 15 to 200 Hz
gain - 50
power supply - -2.5V, 2.5V dual supply
inputs - differential